The purpose of this project is to study the role of sensory function in laryngeal motor control and movement disorders. During the last year the focus has been on the study of mechanoreceptors in an animal model. The effects of conditioning stimuli using different types of stimulation are being studied to evaluate the role of sensation in eliciting laryngeal adduction and abduction reflex responses. Air pulses are being presented to the glottis and responses in the abductor and adductor muscles are being compared. Similarly, the effects of arytenoid cartilage displacement with a servomotor determine whether adductor or abductor responses are elicited. Response adaptation to mechanoreceptor stimulation is being compared with electrical stimulation of the afferents contained in the superior laryngeal nerve. Early and late responses are affected differently by conditioning stimuli suggesting different pathways are involved in suppression. NMDA receptor blockade has been found to suppress only the late responses to electrical stimulation. The long and short term effects of peripheral afferent nerve injury on sensory response adaptation will be examined. Parallel clinical studies in controls and in patients with spasmodic dysphonia or muscular tension dysphonia are being planned. Our purpose is to develop quantitative techniques for the study of laryngeal sensory function in patients with vocal fold motor control disorders.